Electric and hybrid vehicles typically include an alternating current (AC) electric motor which is driven by a direct current (DC) power source, such as a storage battery. The AC electric motor is relatively high power typically being on the order to hundreds of thousands of Watts. Motor windings of the AC electric motor can be coupled to inverter module(s) which convert the DC power to AC power which drives the AC electric motor.
FIG. 1 is a schematic diagram of a conventional inverter system. The system includes an inverter module 20 and an interconnection system 35. The interconnection system 35 comprises an Electromagnetic Interference (EMI) core 30 and an EMI filter apparatus 25.
The inverter module 20 is coupled to the interconnection system 35 by a pair of bus bars 32. The EMI core 30 is located between the EMI filter apparatus 25 and is disposed around the bus bars 32.
The EMI filter apparatus 25 includes an EMI filter card 40 and a pair of bolts 50, 52 which include a positive terminal (+) bolt 50 and a negative terminal (−) bolt 52 for coupling to a DC power source. The EMI core 30 is coupled to the bolts 50 by the bus bars 32. The EMI filter card 40 is also coupled between ground and the bus bars 32 via a pair of wires 34.
The inverter module 20 includes a number of transistors (not shown). Transistors in the inverter module 20 switch on and off relatively rapidly (e.g., 5 to 20 kHz). This switching tends to generate electrical switching noise. The electrical switching noise should ideally be contained inside the inverter module 20 and prevented from entering rest of system to prevent interference with other electrical components in the vehicle. It is desirable to reduce the EMI noise produced by the system.
This configuration requires a large number of components and can be relatively costly to manufacture. The EMI filter apparatus 25 consumes valuable space since the EMI filter card 40 is a relatively large, separate component. This configuration is also susceptible to electrical or EMI noise because it uses a separate connection to the bus bars 32 via the wires 34.
Notwithstanding these advances, there is a need for high current/power, low EMI noise inverter systems. It would be desirable to provide techniques for reducing EMI noise in the inverter system. It would also be desirable to reduce the cost and size of such inverter systems to provide a low-cost, compact inverter system which utilizes fewer parts. It would also be desirable to reduce and possibly eliminate the number of interconnections needed between components of the inverter system. There is also a need for a high current, low EMI noise connection system which can be used, for example, to couple the bus bars to the inverter system. It would also be desirable to reduce the size of the EMI filtering apparatus and the amount or number of capacitors needed for filtering. Other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.